Here's the scenario:
Posted above is the start of my website's title animation.
I have a bunch of letters which I am going to hang off a tree branch or some fixed bar, with string.
A gentle breeze will blow against them causing them to rock (and therefore rotate) gently at different rates according to how large each letter is and how long the string is.
In summary... Uncontrolled variables: Horizontal force, length of string. Controlled Variables: 20N gravity, the relationship between Variable B and horizontal force applied. How far does each letter travel and how fast?
Whoever gives me the information I need will get real life money, according to how much effort is put in.
EDIT: If you're super awesome, you'd let the force of the wind change according to a sine wave with a relatively flat amplitude.
